Vapour Pump Fluids
| Vacuum achievable at 20 °C | mbar | 6.5x10-5 | 1.3x10-9 | 5x10-9 |
|---|---|---|---|---|
| Vapour pressure at 20 °C | mbar | 5x10-6 | 2.6x10-10 | 7.8x10-10 |
| Vapour pressure at 100 °C | mbar | 2.4x10-2 | 6.5x10-6 | 2.6x10-5 |
| Vapour pressure at 150 °C | mbar | 6.5x10-1 | 4x10-4 | 2.3x10-3 |
| Boiling temperature at 1.3 mbar (average) | °C | 160 | 295 | 251 |
| Molecular weight (average) | - | 310 | 446 | 407 |
| Viscosity cSt at 20 °C | 34 | 2400 | 71.3 | |
| Viscosity cSt at 100 °C | 5.0 | 12 | 5.6 | |
| Viscosity cSt at 150 °C | 2.7 | 4.5 | 1.2 |
AP201 Vapour booster pump fluid
Apiezon® AP201 is a hydrocarbon fluid prepared by molecular distillation and protected against oxidation by a thermally stable additive of matched vapour pressure. It has an auto ignition temperature of 305 °C. It exhibits a fair degree of resistance to chemical degradation (so that high throughputs of air and water vapour can be pumped without damage to the fluid) and it can withstand limited accidental admission of atmospheric air at operating temperature. The fluid has low viscosity which permits easy filling and draining. It does not attack synthetic rubbers used for seals and gaskets in vacuum systems. It is non-irritant, non-toxic and environmentally non-polluting.
Edwards L9 diffusion pump fluid
Edwards L9 fluid has been developed for use in Diffstak and diffusion pumps. It is a naphthalene based synthetic material which is ideal for use in applications where silicones (which form insulating films) cannot be tolerated. L9 fluid is rugged, has a very good vacuum performance and gives an ultimate pressure of typically 5×10⁻⁹ mbar (at 20 °C). In addition, the fluid is chemically stable and is resistant to acids, alkalis, halogens and oxides of nitrogen. It does not react with common engineering metals or elastomers. It is immiscible to the common solvents alcohol, acetone and trichlorotrifluoroethane. The toxicity level of L9 is very low.
Safety note: When changing to this fluid the pump should be cleaned using a proprietary fluid. The pump should then be rinsed in acetone and dried prior to re-charging.
